The present invention relates to amphibious vehicles and in particular to power trains for such vehicles.
In one power train layout for an amphibious vehicle, as described in the applicant's co-pending application no. GB0422954.8, an engine is arranged so that its crankshaft drives a gearbox from which road and marine drive outputs are taken. The road drive is turned through an angle of up to 90.degree. by means of a bevel gearbox so as to provide an upwardly angled drive to a continuously variable transmission (CVT) speed change unit of the sort having two pulleys interconnected by a belt, which belt runs in a substantially horizontal plane. The output of the CVT unit then by means of a further substantially vertical shaft drives a differential coupled to the rear road wheels.
A problem with the aforesaid arrangement is that the provision of the CVT unit much above the crankshaft axis tends to cause vibration; while the location of the CVT unit weighing up to say 30 kg increases the amphibious vehicle's top weight. This in turn raises the vehicle's centre of gravity and increases its metacentric height, which deleteriously affects vehicle handling on both land and water.